When pathogens get past those preliminary defenses, your body mounts an immune response. Your innate immune system responds first and employs several types of cells and molecules to fight off pathogens, each with their own jobs.

Unlike bacteria and fungi, viruses exist in a gray area between “living” and “non-living” because of the way they are structured and how they reproduce. As we face down the COVID-19 pandemic, it’s important to understand not only how viruses work, but how our immune system responds.

Contact tracing is the process of working with an infected patient to help them recall everyone with whom they have had close contact, then, warning the exposed individuals of their potential exposure.